1,412 research outputs found
Supersoft X-Ray Sources in M31
The nearby Andromeda galaxy (M31) has been observed with the ROSAT PSPC in a
mosaic of 6 pointings with 25 ksec each. In the paper describing the results on
the total sample of detected sources, Supper et al. (1996) also report the
positions for 15 supersoft X-ray sources and the blackbody fit results for the
brightest of these sources. We report here in more detail on the X-ray spectral
characteristics of all these 15 supersoft X-ray sources. Optical multi-colour
photometric data obtained in 1990 at the Michigan- Dartmouth-MIT Observatory at
Kitt Peak were used originally in the selection process of the supersoft
sources, and are the basis for the finding charts given here for most selected
X-ray sources.Comment: 8 pages postscript incl. figures, Proc. of Workshop on Supersoft
X-Ray Sources, to appear in Lecture Notes in Physics vol. 472 (1996
A method for concentrating lipid peptide DNA and siRNA nanocomplexes that retains their structure and transfection efficiency
Nonviral gene and small interfering RNA (siRNA) delivery formulations are extensively used for biological and therapeutic research in cell culture experiments, but less so in in vivo and clinical research. Difficulties with formulating the nanoparticles for uniformity and stability at concentrations required for in vivo and clinical use are limiting their progression in these areas. Here, we report a simple but effective method of formulating monodisperse nanocomplexes from a ternary formulation of lipids, targeting peptides, and nucleic acids at a low starting concentration of 0.2 mg/mL of DNA, and we then increase their concentration up to 4.5 mg/mL by reverse dialysis against a concentrated polymer solution at room temperature. The nanocomplexes did not aggregate and they had maintained their biophysical properties, but, importantly, they also mediated DNA transfection and siRNA silencing in cultured cells. Moreover, concentrated anionic nanocomplexes administered by convection-enhanced delivery in the striatum showed efficient silencing of the β-secretase gene BACE1. This method of preparing nanocomplexes could probably be used to concentrate other nonviral formulations and may enable more widespread use of nanoparticles in vivo
Chirality Violation in QCD Reggeon Interactions
The appearance of the triangle graph infra-red axial anomaly in reduced quark
loops contributing to QCD triple-regge interactions is studied. In a dispersion
relation formalism, the anomaly can only be present in the contributions of
unphysical triple discontinuities. In this paper an asymptotic discontinuity
analysis is applied to high-order feynman diagrams to show that the anomaly
does indeed occur in sufficiently high-order reggeized gluon interactions. The
reggeon states involved must contain reggeized gluon combinations with the
quantum numbers of the anomaly (winding-number) current. A direct connection
with the well-known U(1) problem is thus established. Closely related diagrams
that contribute to the pion/pomeron and triple pomeron couplings in color
superconducting QCD are also discussed.Comment: 52 pages, 29 PS figures in the tex
250Program overview: Diseases treated, types of transplants, regimens and outcome in an outpatient blood and marrow transplant program
Next-to-leading BFKL phenomenology of forward-jet cross sections at HERA
We show that the forward-jet measurements performed at HERA allow for a
detailed study of corrections due to next-to-leading logarithms (NLL) in the
Balitsky-Fadin-Kuraev-Lipatov (BFKL) approach. While the description of the
d\sigma/dx data shows small sensitivity to NLL-BFKL corrections, these can be
tested by the triple differential cross section d\sigma/dxdk_T^2dQ^2 recently
measured. These data can be successfully described using a
renormalization-group improved NLL kernel while the standard
next-to-leading-order QCD or leading-logarithm BFKL approaches fail to describe
the same data in the whole kinematic range. We present a detailed analysis of
the NLL scheme and renormalization-scale dependences and also discuss the
photon impact factors.Comment: 15 pages, 9 figures, new title, NLL-BFKL saddle-point approximation
replaced by exact integratio
Adjustment to colostomy: stoma acceptance, stoma care self-efficacy and interpersonal relationships
‘The definitive version is available at www.blackwell-synergy.com.’ Copyright Blackwell Publishing. DOI: 10.1111/j.1365-2648.2007.04446.xThis paper is a report of a study to examine adjustment and its relationship with stoma acceptance and social interaction, and the link between stoma care self-efficacy and adjustment in the presence of acceptance and social interactions.Peer reviewe
Magnetic field diagnostics and spatio-temporal variability of the solar transition region
Magnetic field diagnostics of the transition region from the chromosphere to
the corona faces us with the problem that one has to apply extreme UV
spectro-polarimetry. While for coronal diagnostic techniques already exist
through infrared coronagraphy above the limb and radio observations on the
disk, for the transition region one has to investigate extreme UV observations.
However, so far the success of such observations has been limited, but there
are various projects to get spectro-polarimetric data in the extreme UV in the
near future. Therefore it is timely to study the polarimetric signals we can
expect for such observations through realistic forward modeling.
We employ a 3D MHD forward model of the solar corona and synthesize the
Stokes I and Stokes V profiles of C IV 1548 A. A signal well above 0.001 in
Stokes V can be expected, even when integrating for several minutes in order to
reach the required signal-to-noise ratio, despite the fact that the intensity
in the model is rapidly changing (just as in observations). Often this
variability of the intensity is used as an argument against transition region
magnetic diagnostics which requires exposure times of minutes. However, the
magnetic field is evolving much slower than the intensity, and thus when
integrating in time the degree of (circular) polarization remains rather
constant. Our study shows the feasibility to measure the transition region
magnetic field, if a polarimetric accuracy on the order of 0.001 can be
reached, which we can expect from planned instrumentation.Comment: Accepted for publication in Solar Physics (4.Mar.2013), 19 pages, 9
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Whole genome sequencing and the application of a SNP panel reveal primary evolutionary lineages and genomic variation in the lion (Panthera leo)
Background Previous phylogeographic studies of the lion (Panthera leo) have improved our insight into the distribution of genetic variation, as well as a revised taxonomy which now recognizes a northern (Panthera leo leo) and a southern (Panthera leo melanochaita) subspecies. However, existing whole range phylogeographic studies on lions either consist of very limited numbers of samples, or are focused on mitochondrial DNA and/or a limited set of microsatellites. The geographic extent of genetic lineages and their phylogenetic relationships remain uncertain, clouded by massive sampling gaps, sex-biased dispersal and incomplete lineage sorting. Results In this study we present results of low depth whole genome sequencing and subsequent variant calling in ten lions sampled throughout the geographic range, resulting in the discovery of >150,000 Single Nucleotide Polymorphisms (SNPs). Phylogenetic analyses revealed the same basal split between northern and southern populations, as well as four population clusters on a more local scale. Further, we designed a SNP panel, including 125 autosomal and 14 mitochondrial SNPs, which was tested on >200 lions from across their range. Results allow us to assign individuals to one of these four major clades (West & Central Africa, India, East Africa, or Southern Africa) and delineate these clades in more detail. Conclusions The results presented here, particularly the validated SNP panel, have important applications, not only for studying populations on a local geographic scale, but also for tracing samples of unknown origin for forensic purposes, and for guiding conservation management of ex situ populations. Thus, these genomic resources not only contribute to our understanding of the evolutionary history of the lion, but may also play a crucial role in conservation efforts aimed at protecting the species in its full diversity.Environmental Biolog
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